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Topic: Repitching yeast? (Read 3347 times)

I rarely harvest and repitch my yeast and I wanted to have a reality check on how much to pitch into a barleywine I'm planning.

In the photo below you can see the yeast I harvested from 5.5 gal 1.052 bitter. I pulled this from the primary about 1.5 weeks after pitching. I washed once and threw out the bottom 10 or 20% of sediment that looked dark and had hops in it. I poured what was left into three 1-pint mason jars.

According to the Mr Malty calculator, I need 370 billion cells, which, depending on how I set the Yeast Concentration and Non-Yeast Percentage settings, means I need 87 to 436 mL of yeast slurry...or 181 mL if I just accept the default settings. If that's right, I'll need to pitch most of the first two jars. Does that seem right? I'm just a little surprised that I need most of the yeast harvested from a full batch of beer.

Also, I am a little concerned about the quality of the yeast I have. Some of the yeast washing videos I looked explained that the good yeast is the light colored layer that settles on top. I seem to have very little of that. How much of this is good yeast?

Finally, if I'm not brewing until Sunday, should I do a small yeast starter to refresh this?

I would definitely do a starter. I haven't brewed a barley wine, so I couldn't tell you how much you would need. I'll be interested in what others say, as I'm tossing around the idea of brewing my first barley wine soon, so thanks for posting this question.

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Jeremy Baker

"An escalator can never break: it can only become stairs. You should never see an Escalator Temporarily Out Of Order sign, just Escalator Temporarily Stairs. Sorry for the convenience." - Mitch Hedberg

I guess I was hoping for a little more rigor in the method. If the answer is, pitch all of it for 5 gallons of 1.10 barleywine, what about 10 gallons? What if it was 5 gal at 1.08? See what I'm getting at?

Clean, packed slurry will be about 4 billion cells/mL. I'd call it 3 billion/mL to account for lost viability, trub in the slurry, etc. So about 120 mL of slurry would be the target. If I'm reading the volume markings correctly, either the left or middle jar should be about right.

I guess I was hoping for a little more rigor in the method. If the answer is, pitch all of it for 5 gallons of 1.10 barleywine, what about 10 gallons? What if it was 5 gal at 1.08? See what I'm getting at?

You're looking for an exact answer for a question that has a lot of variables! Best to err on the side of pitching more than enough than less than enough. It's very hard to overpitch to the point where it will affect your beer however it is quite easy to underpitch to where it will affect your beer.

OK then. If you want to be more rigorous, I'd suggest making a serial dilution and start counting on the counting slide after you get to around 1 million fold dilution. After that do some vital staining to determine how many cells are alive vs dead. To confirm, I'd recommend plating various volumes of the dilutions on plates and letting them grow out. Then you count the colonies and project the viable cell count. Doing it in triplicate is probably better.

OK then. If you want to be more rigorous, I'd suggest making a serial dilution and start counting on the counting slide after you get to around 1 million fold dilution. After that do some vital staining to determine how many cells are alive vs dead. To confirm, I'd recommend plating various volumes of the dilutions on plates and letting them grow out. Then you count the colonies and project the viable cell count. Doing it in triplicate is probably better.

OK then. If you want to be more rigorous, I'd suggest making a serial dilution and start counting on the counting slide after you get to around 1 million fold dilution. After that do some vital staining to determine how many cells are alive vs dead. To confirm, I'd recommend plating various volumes of the dilutions on plates and letting them grow out. Then you count the colonies and project the viable cell count. Doing it in triplicate is probably better.

I can't tell if there is sarcasm at play, here...

My guess is probably.

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Jeff Gladish, Tampa (989.3, 175.1 Apparent Rennarian)Homebrewing since 1990AHA member since 1991, now a lifetime member BJCP judge since 1995